1. Field of the Invention
The invention relates to a device for heating fluid in a cavity to thermally treat body tissue. More particularly, the present invention relates to an expandable device filled with a conductive fluid and having a bipolar electrode assembly to heat the conductive fluid.
2. Description of Related Art
Application of thermal energy has been used for some time to treat body tissue. One method of controlled application of thermal energy involves the use of a balloon or similar bladder filled with heated fluid. The bladder is placed against the tissue to be treated, and the heat from the fluid passes through the walls of the bladder and into the tissue.
Application of thermal energy with fluid-filled balloons has been of particular use in treating tissue in body cavities of animals, including humans. For example, balloons filled with heated fluid have been used to effect cauterization of a uterine endometrium.
A method is known for effecting necrosis of the endometrium by inserting a distensible bladder into the uterus. The distensible bladder is inflated to a predetermined pressure with a fluid so that the distensible bladder is in contact with substantially all of the tissue lining for which necrosis is desired. The fluid is heated to a temperature sufficient to ablate the tissue lining. The temperature and pressure of the fluid is controlled by means connected to the distensible bladder. The bladder is maintained inflated with the fluid at a temperature for a period of time sufficient to effect necrosis of the endometrium.
Early methods for heated-balloon therapy required the fluid to be preheated outside the body, and then pumped through conduits into the balloon or other bladder. However, such methods may cause heat to build up around the conduits as they pass into the body cavity, which may cause unwanted heating of body tissue adjacent to the entry into the body cavity. Another previous method for heated-balloon therapy involved positioning a heating element coil in the balloon, and causing an electrical current to pass through the coil, thereby heating the coil and the surrounding fluid.
Consequently, there is a need to improve heated fluid systems to provide rapid and uniform heating while at the same time allowing a user to monitor and control the fluid temperature. The present invention satisfies these needs.